Although the chest pain is often severe, some people may only experience minor pain, similar to indigestion. In some cases, there may not be any chest pain at all, especially in women, the elderly and people withdiabetes.

It's the overall pattern of symptoms that helps to determine whether you are having a heart attack.

Waiting for the ambulance

If someone has had a heart attack, it's important to rest while they wait for an ambulance, to avoid unnecessary strain on the heart.

If aspirin is easily available and the person who has had a heart attack isn't allergic to it, slowly chew and then swallow an adult-sized tablet (300mg) while waiting for the ambulance.

The aspirin helps to thin the blood and restore the heart's blood supply.

Cardiac arrest

In some cases a complication called ventricular arrhythmia can cause the heart to stop beating. This is known as sudden cardiac arrest.

Signs and symptoms suggesting a person has gone into cardiac arrest include:

they appear not to be breathing

they're not moving

they don't respond to any stimulation, such as being touched or spoken to

If you think somebody has gone into cardiac arrest and you don't have access to an automated external defibrillator (AED), you should perform chest compressions, as this can help restart the heart.

Chest compression

To carry out a chest compression on an adult:

Place the heel of your hand on the breastbone at the centre of the person's chest. Place your other hand on top of your first hand and interlock your fingers.

Using your body weight (not just your arms), press straight down by 5-6cm on their chest.

Repeat this until an ambulance arrives.

Aim to do the chest compressions at a rate of 100-120 compressions a minute. You can watch a video on CPRfor more information about how to perform "hands-only" CPR.

Automated external defibrillator (AED)

If you have access to a device called an AED, you should use it. An AED is a safe, portable electrical device that most large organisations keep as part of their first aid equipment.

It helps to establish a regular heartbeat during a cardiac arrest by monitoring the person's heartbeat and giving them an electric shock if necessary.

You can read more information aboutCPR and AEDs on the Arrhythmia Alliance website.

Angina and heart attacks

Anginais a syndrome (a collection of symptoms caused by an underlying health condition) caused when the supply of oxygen-rich blood to the heart becomes restricted.

People with angina can experience similar symptoms to a heart attack, but they usually happen during exercise and pass within a few minutes.

However, occasionally, people with angina can have a heart attack. It's important to recognise the difference between the symptoms of angina and those of a heart attack.

The best way to do this is to remember that the symptoms of angina can be controlled with medication, unlike the symptoms of a heart attack.

If you have angina, you may have been prescribed medication that improves your symptoms within five minutes. If the first dose doesn't work, a second dose can be taken after five minutes, and a third dose after a further five minutes.

If the pain persists, despite taking three doses of glyceryl trinitrate over 15 minutes, call 999 and ask for an ambulance.